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Opened 5 years ago

Closed 4 years ago

#302 closed defect (worksforme)

Integration time for pp->bbjj +1jet Order_EW=4 at sqrt(s) = 100 TeV is ~8 days

Reported by: Owned by:
Priority: major Milestone: rel-2.2.0
Component: Unknown Version: 1.4.5
Keywords: Cc:


Dear Sherpa authors,

I have been trying to generate a sample of p p -> b b j j + 0/1 jet with Order_EW = 4; using CKKW for the merging. Its integration step has taken 4 days (for the b b j j + 1 jet integration) so far and Sherpa claims it will take at least 4 days more. This seems a bit unreasonable and I wonder if it is due to a mistake I am making or a bug.

The Run.dat file has been attached.

Best regards, Danilo

Attachments (1)

Run.dat (872 bytes) - added by 5 years ago.
Run card for pp->bbjj at sqrt(s) = 100 TeV (Order_EW=4) generation

Download all attachments as: .zip

Change History (4)

Changed 5 years ago by

Attachment: Run.dat added

Run card for pp->bbjj at sqrt(s) = 100 TeV (Order_EW=4) generation

comment:1 Changed 5 years ago by

PS: Please note that this also happens with other similar processes (Order_EW=0 or 2 and with bbja, jbaa, etc), but for this process in particular it takes longer. For the other processes it can even take 2 or 4 days, which is still a lot, but not as worrying as 8 days.

comment:2 Changed 5 years ago by

PPS: As a final note, I have also noticed that these messages happen often before the start of the integration:

Amplitude::GaugeTest?(): Large deviation {


vs 2.62003930522e-26 => 3.16786596954e-11



Amplitude::GaugeTest?(): Large deviation {


vs 1.19412465114e-28 => -3.60833585233e-12



Amplitude::GaugeTest?(): Large deviation {


vs 4.04840232946e-30 => 1.03543840169e-10



Amplitude::GaugeTest?(): Large deviation {


vs 1.84506829693e-29 => 2.65678590239e-11


comment:3 Changed 4 years ago by Stefan Hoeche

Resolution: worksforme
Status: newclosed

Hi Danilo,

the gauge test warnings are unproblematic as long as the deviations shown are very small (order 1e-12 is ok, in some exceptional cases 1e-10 is also fine). To reduce integration time you may want to try a different scale choice, such as


and/or consider parallelization via MPI (see the section on MPI in our Manual).

Best wishes Stefan

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